Proposals are frequently submitted to standardization bodies, or generally discussed among technology experts, that describe how to integrate, transport and consolidate traditional central office (CO) based voice services (e.g., plain old telephone services (POTS)) over next generation infrastructures such as Asynchronous Transfer Mode (ATM) infrastructure.
In the interim, standards bodies such as the International Telecommunications Union (ITU) have defined a series of standards that are often regarded as the way to achieve this integration. This infrastructure is known as the ATM-Broadband Integrated Services Digital Network (B-ISDN) infrastructure. However, this infrastructure could face scaling and voice quality issues as it simply represents an overlay solution with its inherent issues. For example, the current infrastructure is based on a circuit-based network, which is limited in its numbering and addressing capabilities.
In addition, this new infrastructure will ultimately be based on Internet Protocol (IP), or an evolutionary form of IP. Specifically, the service layer will be fully IP-based and the transport layer will either be IP or ATM. Thus, it would be desirable to have a technology to provide large-scale integration of voice traffic that works on both technologies seamlessly, and yet is able to deliver the connection-oriented nature and the quality of service guarantee that traditional voice service requires.